SELCAL Information

SELective CALling

SELCAL, or Selective Calling, is a signalling system used in conjunction with
High Frequency (HF) radio communications. It is used to alert pilots communicating with ATC of an
incoming radio message on HF. Each aircraft is assigned a 4 letter SELCAL code by ARINC
(Aeronautical Radio Inc.), SELCAL equipment on board the aircraft monitors the HF radios
for incoming signals and will generate an aural tone in the cockpit when the incoming signal
matches the SELCAL code. The main purpose of SELCAL is to avoid having a constant listening
watch on the HF radios to monitor for incoming calls, because the HF frequency is very noisy.
A SELCAL code is made up of two pairs of letters (4 letters), and respects the following rules:

Only the letters A to S can be used.

The letters I, N and O are not allowed.

Duplicate letters in the same pair are not allowed (SEL/AABC or SEL/ABCC are not valid).

The same letter in both pairs is not allowed (SEL/ABAC is not valid).

The succeeding letter in the same pair must be higher than the preceeding one (SEL/ACDB is not valid).

Pilots:

When filing a flight plan make sure you add your SELCAL code in the Other Information section as follows:
SEL/ followed by the 4 letter SELCAL code assigned to your aircraft. Example: SEL/ABCD

ATC:

SELCAL is mostly used by Oceanic Enroute Facilities on IVAO. Check your division's ATC Operations to find out if it is used in your division.
There are 2 methods to call an aircraft using SELCAL. You can either right click on the aircraft's
tag and select SELCAL from the menu, or you can type .selcal <callsign> in the communication
box. Both methods will open the SELCAL window where you can input the 4 letter SELCAL code of the aircraft
in question. Finally just click on TX SELCAL to chime the crew!